1. Field
The present embodiments relate to a magnetic head device.
2. Related Art
Generally, a magnetic head device that includes a slider facing a magnetic recording medium and is provided with a magnetic functional unit on a trailing end thereof is used for reading a magnetic signal from and writing a magnetic signal to a magnetic recording medium, such as a hard disk. The magnetic functional unit includes a reproducing functional part using a magnetoresistive (MR) effect or a giant magnetoresistive (GMR) effect, and a recording functional part composed of a yoke, a coil, and the like that are made of magnetic material and formed of thin films.
The slider of the magnetic head device is pressed against a surface of the magnetic recording medium by an elastic member that is referred to as a load beam. When the magnetic recording medium rotates, airflow (air bearing) running into the space between the surface of the magnetic recording medium and the slider causes the slider to fly above the magnetic recording medium and provides a predetermined flying height between the magnetic functional unit and the magnetic recording medium.
Generally, in a slider of a magnetic head device of this type, a surface facing a recording medium has a positive-pressure surface that allows a flying pressure to be created by airflow, and a negative-pressure-generating surface recessed from the positive-pressure surface. A balance between flying force exerted on the positive-pressure surface and attractive force generated on the negative-pressure-generating surface and directed toward the recording medium allows the slider to be brought to a proper position above the surface of the recording medium and to maintain a stable flying height.
Recently, in order to increase the magnetic recording density and to achieve high-speed recording and reproduction of magnetic signals, a magnetic head device is configured such that the flying height of a magnetic functional unit of the magnetic head device from the recording medium is minimized.
Japanese Unexamined Patent Application Publication No. 10-283622 discloses a magnetic head device that is designed not only to reduce a flying height from a recording medium, such as a hard disk, but also to stabilize the flying height during seek operation in which a magnetic head moves between the inner radius and the outer radius of the recording medium, and specifically to reduce variations in yaw angle.
This magnetic head device has a front dynamic-pressure-generating part on which flying force is exerted, a rear dynamic-pressure-generating part for creating a negative pressure, and a deep cavity located between the front and rear dynamic-pressure-generating parts and on which virtually no flying force is exerted and no negative pressure is created. Thus, a stable dynamic position of the magnetic head is achieved chiefly by flying force exerted on the front dynamic-pressure-generating part and by the negative pressure created on the rear dynamic-pressure-generating part.
As the flying height of a slider in a magnetic head device has decreased recently, variations in flying height caused by changes in air density are becoming a problem. When the flying height of the slider from a magnetic recording medium is small, the flying height easily decreases in response to a decrease in air density according to altitude. This causes the slider to easily come into contact with the surface of the recording medium when used at a high altitude or in an airplane.
The magnetic head device disclosed in Japanese Unexamined Patent Application Publication No. 10-283622 causes flying force to be exerted on the front dynamic-pressure-generating part and causes a negative pressure to be exerted on the rear dynamic-pressure-generating part, thereby attempting to stabilize the dynamic position of the magnetic head. However, since this magnetic head device has a structure in which a negative pressure is created mainly in the rear dynamic-pressure-generating part, a decrease in air density in the use environment may lead to an excessive decrease in the flying height of the rear dynamic-pressure-generating part.
Japanese Unexamined Patent Application Publication No. 10-283622 discloses another embodiment in which a negative-pressure-generating part is provided in the middle section between the front dynamic-pressure-generating part and the rear dynamic-pressure-generating part. The negative-pressure-generating part in the middle section is expected to contribute to the reduced overall flying height of the magnetic head and to a reduced distance between the magnetic functional unit and the surface of the recording medium. However, since a balance between a negative pressure created on the negative-pressure-generating part in the middle section and a negative pressure created on the rear dynamic-pressure-generating part is not adjusted, the negative-pressure-generating part in the middle section may cause an excessive decrease in the flying height of the magnetic head when air density in the use environment decreases.